US2325587A - Conversion of mineral oils - Google Patents

Description

Aug. 3, 1943. D. G. BRANDT coNvERsIoN oF MINERAL oILs ATTORNEY rectifying column yis sent to afsecon'd similar column for the removal-.oi C3 hydrocarbons over-V head, after which the liquid from therbase of this second rcolumn is conducted to a third col.

umn which produces C4'hydrocarbons overhead and a stabilized bottoms product o f the desired vapor pressureY or content of C4 hydrocarbons;

YHeated reboilers are used for each of the rectiy- 1 Iig columns.i Olverheadlreiiux issupplied to each 5` oi' the columns from. condensates of overhead vapors. The rst column may be operated underl f f a considerably higher vpressure than'that of the' cracking unit, forexample, at approximately 409 lbs. per square inch. The' second column is operated at a pressure 'of approximately Zlillbs, per square inch, While the third column may be.;kv operated at approximately 50 lbs. per square inch. l l In accordance with the features and'objects of 7 the present invention, the improvements coin` prise a niethodsfor handling convertedoil prod'- ucts fr'omyanyf type ofA conversion apparatus.

- The.'Y method particularly comprises the steps of irst/eliminatingvthe veryheavy constituents such as -fuel Voil notdesired for furtherprocessing,

from the con-version products, using the gasoline Y* and cycle'cilsicontained inV therremainderv ofthe conversion productsforcondensing and absorbing all ofrthe products'except thevfrelatively dryA ,j gases such as hydrogen and' methane, `and virac- Y Y tionating the condensed conversion products into marketable fractions,4 and :fractionsltobere'- Hturnedand reprocessed in the conversion yap-V rOtherYfeatures, Volojectsand advantages of the process and apparatusofthe present invention, will `be apparent to v.those skilledfintheartrfrom i the following- Ymore detailed description. taken in connectionv with the 4-accornpanying drawing, in

is `vaporzed by a substantial reduction in pi'esfl sure Which occurs inl theV line l2. The fuel oil 'constituents remaining unvaporized inthe still ifi areconducted through' a line It and discharged from the system by means of a 'pump mounted therein and passed throughfa cooler` Y l y The vapors formed in the concentrator ifi will cornprisegas o il constituents aswell as lowerY boiling hydrocarbons which 'may'.j'be dissolvedpin the liquid oil in the bottom of the chamber t un der the pressure and temperature conditions 'inaintained therein. These vapors are conducted from thestill lli through alvapor line i8, acondenser 2t andaV linei22, into a receiver and gas fiseparator V2li. `'Anyuncondensed gases are dis- Vfcharged'vfromf ther receiver B through an automr maticpressure valve lcontrolled line 2. AThe disf tillatejcollected the bottom of the receiver is utilized for effecting the cooling of the cracked yproducts from the chamber I and is therefore y Y Withdrawnthrough af-lineri and forced'bymeans Y of. a pump mountedftherein into the-'sprayzring il). .Apart or all offthe cooling may he `effected bye' int'roducingmcool distillate at ,al :tangent into thecrackediproducts entering the funnel@ from a branch line 29. Any excess of this distillate over; that required'foreiiecting the cooling o1?l the, cracked products is discharged through ar valved, line .30..v AThe' vapors nowV rem iningmn-4 condensed in thev chamber kii and Ywhicl'i'hiwe beenjcooled by oil sprayed from the ring i'novv Y include asubstantial proportion -of constituents v `boiling abovezthe'boiling point opgosoline as Well as hydrocarbons boiling, belowthe'initi'al boiling point offgasoline, and uncondensab-le gases such as hydrogen,v methaneethane, ethyl-ene, etc. These vapors arelidischarged from the upper partroff the chamber Y.8 through a line 32 in which isr mounted a heat exchangerfor `partially cooling kthe/vapors,preferably-by heat exchange with oil V,charging stock ,or withv feed stock for the pipe diagram of anrapparatus particularly: adapted for A carrying outVV theimprovements of the present Y invention may helapplied lto' the V conversicnof The particular improvements or the presentY petroleum, oils'- as carriedout'inany ofthe usual "tube Aor tube andv chamber cracking processes.V

' The highly.` heatedconversion products. from aV vrpipe stillfurnace or furnacediorcxaniple. such as described in application Serial No'.r 158,9sl0 are Yconducted into the apparatus shown in thedrawing While at a high temperature through a line 2 a and introduced, preierablyat atangent,into the fuppcr portion yoi an enlarged. (broken) reaction chambercomprisinglthe upper portionv of` a `vertical tower. VThe .highly'f-vlfieated 'partially cracked lproducts introduced into the chamber d flow `downwardly through thechamber andV pass through a funnel 6 which extends into a cooling.-

chamberv Thelliquidiportion oithe vconversion AIproductsxi'lovvs to the'l bottom ofthe chamber .3Y whilethe vapors pass aioundthe lovverend of the funneland are-subjected to intimate contact with a coolingliqu'id preferably-a distillate, introduced. through l'a spray fringC, it. Sufficient -oil )is introduced through .thisspray ring to quickly cool the vapor productsfto a' temperature at Whichrany'iuelfoilltype constituents Which-'may be in the vaporslwillbe condensed. v

i A11 ,of Y theuquidmateriarin the chamber a ows' VAinto the narrow bottom sectionv of the chamber andis discharged through a floatvalve 38 may be conductedrdlrectly through the valve Y therein without=being passed to the separator 32,

y aheat exchanger 57,8.,-a`line 61a cooler ilrnoiiiit'- @drin .linef and finaliymto the lower perdonar controlledV line 'lzjinto a1concentrator M in which allor" the :constituentshot desiredjn thejueloll still heater or heaters used in connection with the processjf, The products in the llnefl are fused'Y which arepassed fromthe chamber 42through'a line 44 Aback into the line 38 beyondvthe valve .aSIShQWn-f Y The portionV of the' oil constituents thel'ine but theproducts in the latenportiorrof this line are conducted-through a yheater' lrnrounted in the lowerhortionof a fractionatingtower 8 to maintain the desired temperatureY therein. TheV productsYintrodilcedl into ythe Yheater-i5 are, dist charged through aline 50 and conductedinto, a

further heater i572i mounteilin j the lower portion oiafractionating tower 5,4, Y

The passingpj the conversion products throughk Y the.heaters 341,.:16-and 52, eifectsaY substantial coclingfand condensation of the products, andthe mixture introduced, into the heater .Tg2 isdisL Qharsed, through a linev 56 and passed. through Vay separator-absorber*6ft; lThe excess of the con- Ce.,rltrritli.distillateproduced in the operating matically controlled by the Ypressurecin the ore-k-` Vceiver e8 so thatthe amount lof coolingwater supplied will be increased IVif Ithe pressure rises f above. a predetermined pointsetfor operating the:

Water supply valve. Although the normally gase- .ous jhydrocarbons will havenbeen removed hin previous yelements of theapparatus, enough will still remain along with C4 hydrocarbons for Amaintaining the back pre'ssurevfromfthe receiver 98.

l The high bolingfconstituents introducedinto' the tower S include those immediately-higher boiling than -the*gasoline,V asr well` as relatively :heavy gas oil constituents.` yVS/hilethgese products may be collected atthe bottom of the toweras a single fraction anddischarged through Van automaticv oatrvalve controlled line 102, the iractionation is preferably so Vconductedqthat a; side stream suitable for` furnace oil iswithdrawn. Ac-

cordingly, provision is made for withdrawing such aside stream iromone or, morejmid-,points in the tower above the inlet, as shown, into aV fline |55, by which itis passedY into a stripping column li. This side stream Will comprise a fraction immediately higherboiling than the gasoline product and be'suitable as alight furnace oil.Y The side stream is stripped of light constituents suchV as those boiling within the, gasoline range, by introducing gas vor. steam into the bottomof the stripper Hi8. The removed vapors and stripping .mediumare passed; into the tower 36 above the point of withdrawaly of the side stream. lThe stripped fraction is dischargedthrough aline H0. and passed through a, cooler H2 and discharged through a valved line vI Hl.. A portion of the Ycooled furnace oil may be passe'dfrom'the line lliifthrough a linerllgby apump therein, into the absorber 64 to supply all ora part` of the absorptionrv oil used therein. f f c In controlling the temperatures maintained in the' bottom of the towers 36, 48 and llprovision is made for lusing valved by.pass lines between i ,the inlet and outlet lines for? these heaters as shown in the drawing. It will be noted that thel pressure is reduced successively through the towers from leftv to right and that considerable vaporization will be effected because of this pressure reduction. The-high boiling condensate, which may be regarded as a relatively heavy gas oil, discharged from tower r36 ythrough the lineV iii2,may be returned-to the heater or heaters of the conversion unit and resubjected iso-cracking conditions for example, in the manner described in said pendingapplication. f

"The process as described above'in connection with the yconversion unit shown in the drawing. has several distinguishing. features'which con-j' tribute'to the economy -and'ease ofhandling the converted materials( For example'itwill be noted that while normally gaseous conversion stocks are produced, there isno pointin thesystem where it n is necessary topump oir-compress gases'. The use of the separator 64 eliminates a very substantial proportion by `volume of ythe vapor A`mixtures' whichare normally handled in the fractionating equipmentopresent 'dayfcracking units. The

Vlight hydrocarbons recovered inthe system for retreatment, are recovered, as liquids without the necessity of'compressing gases.

VOne of the importantfeatures'of the process of the present invention-is the retention of high boiling point hydrocarbons in the mixture of conversion products'so that their presence is utilized in' they handling of ther low boiling" constituents particularly normally gaseous hydrocarbons. Iny

the'operation, the'excessively heavy, fuel oil type,

hydrocarbons are( separated from, theconversionk products in the 4chambert. w lThe nextstep comprises the eliminationV of the excessively volatile or gaseous,L constituents. Finally, the c desired gasoline range hydrocarbons lare `recovered from the mixturewhichvincludes lower andhigher boiling hydrocarbons, Thismixture may ,be

- Vhandled in Vthe'manner described in connection ents lower boilingithan gasoline may be fractionatedfinto moreor lessv individual classes of hy- Y drocarbonasuch as C3 and C4 groups, each of t which may be separately polymerized or utilized withthe drawing or. by various-other methods to separately .recover the. gasoline range constitu-5 entstheV lower boilinghydrocarbons, andthe higher boilinghydrocarbons.`V j c Asacfurther example, the mixture containing thegasoline and adjacent lower'and higher boilinghydrocarbons V(after being freed of excessively heavy and light constituents) may V,be separated into several fractions,` after which theconstitufor various purposes in Vthe industries. i

The process of the. present invention may be applied to the handling of' a mixture of con- Version products regardless Voi' the type of cracking operation used for vtheir production, Whether liquid phase, VVapor phase, or a mixed liquidand fil claims. Y Certainlsubject-matterdisclosed herein is;V disvapor cracking operation. ,n handling the products ironia liquidphase operation, the excessively light gasesare preferably rst eliminated from Y the mixture,v after which the next lighter constituents may be successively rremovedgbyiractional distillationp (Jn-the other' hand, theproducts from a liquid 'phase conversion operation may be handled by rst eliminating 'the excessive- 'processes and that many modifications-may be madein the apparatus andthe operations carried out without departing from the spirit and scope of the invention, as de'ned by the accompanying closed and claimed vin applicants application .Serial No; 371,929, iledvDecember 27th, 1940. Having thus described the invention in its pre-` c l' ferred form, what is claimed as' new is:

ffl. In the conversion or' 'nydrocarbonsinto antiknock gasolinein whicha vapor' mixture cornprising the conversion products fis produced ,in the conversionV operation, said mixture containing the constituents of the desired gasolinel product as wellv as higher and lower boiling readily lcondensable ,constituents f' and uncondensable gases, the ,improvement which'comprises subjecting the vapor mixture to cooling and condensing conditionsftor produceva relatively high boilingr condensate therefrom` of higherV boiling point than pressure' distillata'subjecting theremaining uncondensed VAvapors and Ygases to further condensing conditions to condense all of the remainingv readily condensable constituents) passing the resulting condensate and uncondensable gases into the lower portionv of afscrubbing tower'n which apache? theluicondensabie are separated out land filmil? thrvllsh the tower,l "the son` mamen aigaponmggconaenss. mm the* `of said `town and it! um, vsrdlrftherethmgn macinate @permutas ,sparring-threesome wwe-sns me the portanti said meer, discharging the fun: gases top of `the towerand t ,Mounting thegcombinedcmdensates includafgsaidmgh toning @sensateandaba soedf Vgeen i s cmsutuenis coilectecfnrtne tomb! the towerto separately rever thedesired gasolinefpmduct and `point 'condon- 2. The Vprocess as definedbyclaim 1 in aaien-a relatlvelyxhlghj superati!iospheric :pressure is l t maintained in said tower and fin whichfthe V; sie (constituents, @condensatie gases, ad imei o il type: hydrocarbons, the improvement `which comprises eliminating fufelf oil" constituents from f the, mixtureg thereafter subi ectingf thefr'emainder of the mixture to acond'ensingoperationinwhich thefradily Conderisaiile constituentsare condenses to producevl s fnignfpoiung distillate and-a final .condensate,l jpa'ssing the Vfinal condensate and normally `uricr'ondensablelga-ses into an absorber and passing 'the gases' in` intimate contact with an absorption medium theiexnunaereondiand scrubbingpemtionsare conducted under suchlconditonsjthat mbstantiailyno 'Ca or higherhydrocarbons are dischargedfrom the top eign-1&1 n" im@ `the condensatemixture recoveredV in the tionsada'meu to'absorb substsnuany snor the C; hydrocarbons, mixing the resulting "rich absorb` tionmedium with the condensate introduced into the absrberijarid-ps'singAthegrsulting'rnixture into a highpressurerectifying towerinwhich lthe mixture 1is` rectied under conditions 'adapted to produce a'bottomsproduct substantially trece! Cz andlower` boiling constituents, passing a vapor fraction discharged the` uppergpart of the rectifying tower and comprising C2 and lower boiling constituents as well as some rCs'hydrocarz son into aseondfaosorber in intimate contact offsaidtower Vis subjected to a rectiiicationoper.-

ation at a pressure substantially higher than that `maintained in said towerto eliminateany dis-Y j solved hydrocarbons below Cs.-`

C d. 'Ihe process of handling the conversion products of a. thermal conversion operation irl-which @such products include hydrocarbons within the range of fuel oil through uncondensable gases of the type "usually produced in thermal conversion operations, which compriseseliminating the fuel ;oi1\constituents from thei mixture "of conversion productsgthereafter condensing all of the readily Vcondensable constituents including Ca hydrocar`` with an sbsorpuonfmedium cosaprisiegsald anni4 boiling distincte tefsbsorbsuestenusiiy all of the Cs hydrocarbon, and passing the rich absorptionmedium from said second absorberin-` j to said rectifying tower to befractionated therein `along with-the condensate mixture introduced thereinto. t 6. The `improvement inthe conversion of hy,- droca-rbons as defined by claim `1in which the l condensate mixture recovered'in the bottom of bons as a single condensate andfractionally disz tilling and rectifying theresulting `condensate in 1 a serlesof fractionating towers, said condensing operationincludingthe passage of Vthefuel oil-v iree conversionproductsinitiallyA in vapor form through the lower portion of each Ofsaid series said scrubbing tower is passed into a highpres-V sure fractionating tower andtherein subjected to "rectifying'conditions adapted to produce a bottoms product substantially free of C2` and lower boilingconstituents, and in which a vapor fraction discharged fromthe top of the fractionating tower and comprisingCs and lower boiling conl stituents as well as some Ca hydrocarbon is passed tinto alsecond scrubbing tower in intimate confof fractionating towers in indirect heat exchange Y t with hydrocarbon constituentsinthebase ofsaid towers vvljrerebyl 'heat isV supplied to-said` towers and saidvaporsare cooled and progressively condensed, separating-gasesincluding Cz hydrocarv bons notreadily" condensable from saidcondenf sategfseparaung a high boiling condensate in the A* progressive condensing operation and passing it- `in intimate` contact` with said `separated gases,

mixing the resulting high boiling `condensate containing absorbed 'constituents with the condensate separated from saidgases, passing the result- I ing `condensate `mixture` including Cs and some `absorbed Cz hydrocarbons-ii'xtotheV rst said" `i'ractlometting towers and. therein rectifying the mixture under-[conditions adaptedto remove `overheadsubstantially only Cs and lower hydro-v carbons." passing the remainder of' the condensate ffrom said rsttower into the second `tower of said series and rectifying the same ltherein to produce overl'iead "ar C: hydrocarbon condensate,l passing Y,

condensate from said second tower to thethird 5. In the conversion of Vhydrocarbons into1 anti.

lthle conversion Yproductsis produced in the-'cori-V version operation,` said miirtnl'er containing `the constituents of the desiredv gasoline product as@ well ashigher andlowerboilingreadily condens'-` knock gasolinefin which .a 4mixture comprising tact with an absorption medium adapted tolabsorb lthe C3 hydrocarbon, andpassing the'rich absorption Vrnediumvfrom Vthe second scrubbing tower into said fractionating tower to be frac. tionated therein.. Y

knock gasoline in whicha'mixture comprising the conversion products is produced in the convery sionoperation, said mixture containingrthe constituents of the desired gasoline product as well as higher and lower boiling readily condensable constituents, uncondensablc` gases, and fuel oil typehydrocarbons, the improvement which-comprises separating the/fuel oil constituents from vthe mixture at a substantial superatmospheric 1j pressure, condensing the remaindercf the readily Y condensable' constituents including C3 hydrocar- `bons asa single condensate, separating the resulting `condensate from uncon d ensableY gases,

passing all of thetcondensate into a' fractionating Qtower andthereinrectifying'the condensate mixture to remove overhead any C2 and lower hydro'- carbons which may havebeen contained in the condensate mixture, dlstilling the separated fuel Y, oil constituents at reducedprssure to producen V'high -bjouing distiuate, passing` said .high boiling* `distillate intintimate contact with the hydrOCarlA bons removed overhead from-.said fractionating towen'frortheabsorption of any C3 and `higher `"hydrocarbons contained therein, and mixing the 'resultinghighboiling distillate and absorbedl con-'f st ituentswith the 'condensate-mixture prior totV 7. In the conversion `ofhydrocarbons into antisubjecting it to rectication in said fractionating towenj, l' my ,t ,8f In therconversion of hydrocarbons into antiknock gasolinefin which a vapor mixturecomp rising the conversion products is produced in Y the conversion operation, said mixture containing the` constituents ofthe desired gasolinerproduct aswell ashigher and lower boilingvreadily Acondensa-ble constituents and lightv hydrocarbon gases, the improvement which comprises Vsubject,-

ingY thelvapormixturefto cooling and condensing l conditions tocondense all of the readily condensf ablefconstituents, passing the resulting condensate including retained light, hydrocarbon gases Yinto the mid-"portion" of a high pressure fraction ating towerin which the condensate is subjected to rectificationunder conditions adapted to produce a liquid bottoms product substantially free of C2 and-lower boiling ,hydrocarbon gases, cooling the Vaporsat the ktop of the `fractionating tower to provide a low boiling reflux liquid, for the top ,oriy the tower, passing thevsaid reflux liquid` lcounter-current tothe vapors and Vgases in the upper portion of the tower in the Vabsence of introducedhigh boiling Vconstituents to aid in the an absorber separatelfrorn said tower, passing the saidvapor fraction in` said absorber in intimate Contactv withanabsorptionmedium adapted to recover substantially all of the lC3 hydrocarbon introduced into the absorber, and passing the rich y,absorption medium from saidabsorberinto the midportion of said high pressure fractionating tower and subjecting it to rectincation therein along with said condensate introduced into said tower.V l ,im t,

9. 4In-jthe conversion of hydrocarbons as dened by claim 8 in which the condensate is rectifled4 in said iractionating to-weri at a pressure of at leastabout 500 lbs. per square inch. o

10. In the conversion of hydrocarbons as de# ned by claim 8 in which the pressure maintained insaid Vabsorber is substantially equal to that maintained in said fractionating tower.

i DAVIDVG. BRANDT.V Y

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